VEGA VEGAMET 391 4 … 20 mA_HART - Manual (Page 42)

42
8 Application examples
VEGAMET 391 • 4 … 20 mA/HART
36032-EN-130701
1 2 3 4 5
Fig. 15: Display indication of a pump control
1 Symbol activated pump control
2 Relay 1 is assigned to the pump control
3 Relay 2 is assigned to the pump control and signals failure
4 Relay 3 is assigned to the pump control
5 Relay 4 is free or not assigned to the pump control
When the level was not changed for a longer period, always the same
pump would have been switched on. Via the parameter "Changeover
time", a time can be preset after which a forced changeover of the
pump is carried out. Which pump will be switched on depends ont he
selected pump mode. If all pumps are already switched on, then the
pump still remains switched on. These function can be only adjusted
via PC and DTM.
Note:
If the pump is already switched on when activating the forced
changeover, the timer will not be started. Only after switching off and
on again, will the timer start. If the switch-off delay is set, it will not
be taken into account, i.e. the changeover is carried out exactly after
the preset time for the forced changeover expires. A preset switch-on
delay, however, is taken into account, i.e. the forced changeover to
another pump is carried out after the preset time expires. Before the
newly selected pump switches on, the preset switch-on delay for this
pump must be expired.
With a pump control, there is also the possibility of switching on pump
monitoring. For this purpose, a feedback signal is required on the re-
spective digital input. The digital inputs are assigned 1:1 to the relays.
Digital input 1 acts on relay 1, etc.
If the pump monitoring for a relay was switched on, a timer is started
when the relay is switched on (time allowance with parameter "Report
time"). If the checkback signal comes from the pump on the respec-
tive digital input within the defined report time, the pump relay remains
energized, otherwise the relay is immediately switched off and a fault
signal outputted. A fault signal and switching off of the relay is carried
out even if the relay is already switched on and the pump checkback
signal changes during the running time of the pump. In addition, a
switched-off relay of the pump control is looked for and switched
on instead of the disturbed relay. A Low signal on the digital input is
evaluated as a pump error signal.
The fault message is cancelled when the signal on the digital input
changes to "Good" or when it is reset via the "OK" key and selection
Option forced changeo-
ver
Pump monitoring